Thread: Electical Panel/Sub Panel Question

I have a question from an inspection that I did today on the electical system. There is a main disconnect outside at the meter base. There is also a main disconnect inside at the main panel (marked - main princaple). It is my understanding that if the main disconnect is outside then there is to be no disconnect in the panel inside which is now a sub panel. The white and grounds are seperated like they are supposed to be. If this is not correct does anybody have an idea how to write this up in the report. I think it needs to be written as a SAFETY ISSUE but not sure.

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There is no problem with the interior sub panel /remote panel having a main breaker.

The exterior breaker is your Service Equipment, and the interior is your sub panel / remote panel.

Originally Posted by Michael Musgrave

I think it needs to be written as a SAFETY ISSUE but not sure.

As long as the neutrals and grounds are separated with the neutral isolated from ground as it is supposed to be ... that type of installation is actually SAFER than just the main disconnect outside.

Think of it as a "panel main" ... now what could be safer than having one main for each panel in addition to the branch circuits? Hard to get much safer than that (presuming, of course, that all else is wired properly).

Michael...

The 2011 NEC is going to require two main breakers so it is a good thing this house already has them installed. Some HI's on this board would write up not having two main breakers as a safety issue and chastise the electrical contractors who only install one main breaker as cheap and cutting corners because the code is only the minimum and should not be followed but improved.

James, do you have a link to the 2011 Code change requiring two main breakers? I have not seen or heard anything about this.

Originally Posted by James Duffin

Some HI's on this board would write up not having two main breakers as a safety issue and chastise the electrical contractors who only install one main breaker as cheap and cutting corners because the code is only the minimum and should not be followed but improved.

And every 15 amp circuit should be 4/0 to make sure there are no voltage drop problems -each receptacle on its own home run too.

Thank you for all the answers. I guess that I have been mistaken about this.

Michael....

I owe you an apology. I made a smarta$$ comment based on the comments on another thread (which you probably have not even read) but you deserved a serious answer because you asked a serious question. So I apologize to you and welcome you to the forum.

James, That is ok and thank you

Originally Posted by James Duffin

Michael...

The 2011 NEC is going to require two main breakers so it is a good thing this house already has them installed. Some HI's on this board would write up not having two main breakers as a safety issue and chastise the electrical contractors who only install one main breaker as cheap and cutting corners because the code is only the minimum and should not be followed but improved.

That is as ignorant statement as they come,one gets what they pay for & low bid means minimum code, adding extras is what loses bids, & if one is dealing w/ tract homes I am sorry to say a buyer is bloody lucky if it's even meets minimum codes. That latter part of my post is a sad state of affairs w/tract homes but they are not built w/ a Mike Holmes unlimited budget, that is living in a fantasy world they end up being built as cheap as they can get away with.

For JP
SUB-panel
RES

PART 1

FLEET TYPE SUBMARINE
MAIN AND AUXILIARY POWER



Sub Elec. Home Page

E. PANELS AND SWITCHBOARDS

7E1. General maintenance of panels and switchboards. Panels and switchboards should be wiped frequently with a soft brush having no metallic binding. If it is necessary to clean off anything other than dust, a soft flannel cloth or a piece of chamois should be used. Cotton waste or cloths that leave lint must not be used. Frequent examination must be made to insure that all connections are tight. The condition of the wires behind the board should be checked periodically. The tendency of the ship's structure to weave sometimes causes enough movement of the wires behind the board to result in their abrasion and consequent breakdown. Surface moisture must be kept at a minimum on all panels to hold up the circuit insulation resistance readings. Its presence on a panel will often account for low circuit insulation resistance readings. If it becomes necessary to remove moisture, use a flannel cloth. Alcohol must never be used for cleaning panels. This substance is not only inflammable, but its use will break down the finish surfaces of panels and of the instruments mounted on them. The use of an approved lacquer is recommended since it not only improves appearance, but also produces a polished surface which does not absorb and hold moisture.

116
G. CONTROL PANEL

17G1. General. Figure 17-34 shows the repeater, control, and follow-up panels. The control panel is used for controlling the operation of the master compass and for indicating conditions of operation such as current and voltage values.

243
Figure 17-34. Schematic diagram of gyrocompass system.

[quote=Ralph Stakely;128332]For JP
SUB-panel
RES

PART 1

FLEET TYPE SUBMARINE
MAIN AND AUXILIARY POWER



Sub Elec. Home Page

E. PANELS AND SWITCHBOARDS

Ralph,

You wouldn't by any chance be an ex-bubblehead would you?

nah USAFSS.. Just yanking Jerry Peck's chain.. He hates it when someone says "sub"panel..

RES

Originally Posted by Ralph Stakely

nah USAFSS.. Just yanking Jerry Peck's chain.. He hates it when someone says "sub"panel..

RES

Good for you, he is not going to win that arguement.

But everyone has their pet peeve, I can't stand it when somebody calls something "110", "220", "440" as they no longer exist.


It's all in good fun.

Just wondering what's the thinking is on why remotes have to be seperated at the Ground/ /neutral when they go back to a SEP where there, they are combined?
Here Jerry, sub, sub sub sub....HA HA

Originally Posted by Marc M

Here Jerry, sub, sub sub sub....HA HA

Starboard engines full ahead, port engines full astern, WWII mine field straight ahead!

Hard-a-port!

Dive! Dive!

Originally Posted by Marc M

Just wondering what's the thinking is on why remotes have to be seperated at the Ground/ /neutral when they go back to a SEP where there, they are combined?

The grounding conductor is not intended to carry any load current, it is meant for equipment ground and to carry fault currents. By bonding the grounding conductor to the grounded conductor at the downstream panel any unbalanced load current will be carried across both conductors.

Originally Posted by ben jacks

'And should a lightning stroke or hi-voltage transient cause a termination breakdown of the neutral connection of the 4-wire parallel hookup, then all of the equipment panels and other plugged-in grounding devices become a grounded energized potential.'

The grounded condition becomes a dangerous hazard for anyone in a touch-step situation and for swimmers escaping from a sinking sub-vessel.

Of course whenever the system has been compromised (and I've had my fair share of dealing with systems compromised by lightning strikes - I haven't seen anything quite so bright as a distribution frame being arc-welded across a room) there is the potential for stray current issues. However in a properly designed system (and this is why balanced load designs are so important) the current traveling on the grounded or grounding conductors should be minimal if the system is otherwise intact.

Right on thanks yall.

Having been in the business for a number of years, I'm always interested in explanations of exactly HOW a residential service can be balanced.

Once any 240 volt loads are counted it is a crap shoot as to what loads will be applied and when. A perfectly balanced panel one minute can have all the loads on one hot leg the next.

Balanced loads are something attempted in commercial and industrial work. In the residential world it is a pipe dream.

Originally Posted by Bill Kriegh

Having been in the business for a number of years, I'm always interested in explanations of exactly HOW a residential service can be balanced.

It's all relative. The nature of residential use is such that there will be intermittent loads. However there are small things you can do, such as putting the refrigerator and chest freezer on different legs. On average you'll likely have 13A on the neutral from either of the two loads. But that should the two be on at once, instead of 25A on the neutral leg you might have 2A instead.

It's not something to attempt to perfect, rather something to be aware of. And really, all it usually means is moving a breaker up or down a position so it's no big deal in the long run.

Originally Posted by Corn Walker

It's all relative. The nature of residential use is such that there will be intermittent loads. However there are small things you can do, such as putting the refrigerator and chest freezer on different legs. On average you'll likely have 13A on the neutral from either of the two loads. But that should the two be on at once, instead of 25A on the neutral leg you might have 2A instead.

It's not something to attempt to perfect, rather something to be aware of. And really, all it usually means is moving a breaker up or down a position so it's no big deal in the long run.

And not worth worrying about. The next occupant will use a different receptacle for the freezer, won't have one, etc.etc.